1. Field of the Invention
The present invention relates to a gate driver and a circuit buffer, and more particularly, to a gate driver capable of realizing a high output voltage and a circuit buffer for constructing the gate driver.
2. Description of the Prior Art
With the popularity of liquid crystal displays (LCD), LCD driver integrated circuits (IC) are becoming increasingly important in the market. A general LCD applies a dual scanning method, which requires a gate driver and a source driver. The source driver outputs voltages to the LCD panel according to pixel data in order to switch liquid crystal molecules for determining gray scales of pixels. The gate driver may turn the liquid crystal display unit on or off via a high voltage.
A driver IC of an LCD uses low voltage circuit elements (having a withstand voltage in the range of 1.5-1.8V), medium voltage circuit elements (having a withstand voltage in the range of 5-6V) and high voltage circuit elements (having a withstand voltage in the range of 25-30V) for its process, which is a mixed-mode process having three types of circuit elements with different withstand voltages. The low voltage circuit elements are usually used in digital logic circuits. The medium voltage circuit elements are usually used for driving the image data (i.e. the source driver). The high voltage circuit elements are usually used in the gate driver. Since a wide variety of circuit elements are required, higher numbers of masks and layers may be needed for the LCD driver IC process, which results in a higher cost.
Thus, there is a need to provide a novel structure of an LCD driver IC that uses fewer numbers of masks and layers for the process.